what is the vallancy. explain it please.?
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Answer:
In chemistry, the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules
The valency of an element is a measure of its combining power with other atoms when it form chemical compounds or molecules. Valency is the combination power of an element. Elements in the same group of the periodic table have the same valency. The valency of an element is related to how many electrons are in the outer shell. The number of bonds that an atom can form as part of a compound is expressed by the valency of an element. The combining capacity of an atom is known as valency.
Concept of Valency
Noble gases have a completely filled outermost shell and that's why they are least reactive. Other elements reactivity depends upon their ability to attain the noble gas configuration. In this section, we shall learn more about the valency of an atom.
If the outermost shell has 8 electrons then the element is said to have a complete octet. By gaining, sharing and losing the electrons, the atoms complete the outermost orbital and make an octet.
The capacity of an atom is described by the total number of electrons lost or gained or shared to complete its octet and it also determines the valency of an element.
How to find valency of elements?
As we know, the number of electrons in the outermost shell of hydrogen is 1 and in Magnesium it is 2. Therefore, the valency of hydrogen is one as it can easily lose 1 electron and become stable. On the other hand, that of magnesium is 2 as it can lose to electrons easily and also attain stability.
Furthermore, it is not only determined when an atom loses an electron. For example, fluorine has 7 electrons in its outermost orbital. It is hard to lose 7 electrons and so it completes its octet by gaining one electron. Since, it gains one electron its valency is 1.